On 29 November 2015 at 17:31, Eric Muller <eric.muller@efele.net> wrote:
 
May be it's time to move the effort to, e.g., OpenStreetMap?

Either OSM, or maybe Natural Earth [1]? They do have some existing data, but it's old and not as detailed [2].

John.

[1] http://www.naturalearthdata.com/
[2] http://www.naturalearthdata.com/downloads/10m-cultural-vectors/timezones/